So I tried uninstalling Razer Synapse and that fixed the problem. Luckily the headset works without the any additional software. He won't be able to change the lighting on the headset but it's otherwise fully functional which is good.
I did initially have a poke around inside Synapse to see if...
So I've bought the aforementioned headset for my son (had Christmas early this year) and it's been great for a couple of days.
The problem started today when out of nowhere Youtube videos have no sound when playing in Chome. Tried out some games in his steam library and they are all working...